一种基于智能卡的微控制器

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1、ConnectionofaSmartCardtoaMicrocontrollerThiscircuitrycouldbeusedfortypicalmicrocontrollerbasedsmartcard,e.g.SIM(=smartCardforGSMmobilephones).Itwillworkfor5Vsmartcards.For3Vsmartcardsthevoltagesshouldbeadapted・ThecircuitrycansupportthestandardISO/IEC7816-3switchon/offsequ

2、ences.Thissequencesarecontrolledbythesoftwareoftheterminal・Mostofthesmartcardswillwork,ifthedriveronterminalsidesupportsatleast20mAoutputcuiTentforVcc.Forsmartcardswhoneedsmorecurrentaswitchtransistorbetween+5Vandthesmartcardon/offportoftheterminalshouldbeplaced・Thisexamp

3、lesneed3outputand1in-/outputportontheterminalside.Oneportcouldbesavedbyacapacitorgeneratedresetofthesmartcard,withthedisadvantageofaincorrectswitchon/offsequence・Clocksourcecouldbeeveryfrequencyfrom1MHzto5MHzforatypical9600bit/sdatatransmissionwithstandarddivider372theclo

4、ckshouldbe3,5712MHz.InstructionsforSmartCardcurrentmeasurementAusualsmartcarduseaVccof5V+/-10%(4,5V-5,5V)andatypicalcurrentof10mA.Thismeansthatanoperationattheminimumvoltageof4,5Vispossible・WiththeformulaU=R*I<=>R=U/Iwecancalculatethataresistorwiththevalueof5()Ohmbetweens

5、martcardandVcccanbeaddwithoutanyproblems(iftheterminaldelivers5Vsupplyvoltage).Withanoscilloscopeitisthenpossibletomeasurethecurrentasavoltagedropoverthisresistor.Iusea47Ohmresistor,becausethisvalueisastandardvalue・AgoodideaistousetheI/OlinefortriggeringifyouwanttodetectE

6、EPROMwrites/eraseswhenthesmartcardsexecutesaAPDUcommand.Withthisassemblyitise.g.easytomeasureEEPROMwrite/eraseaccesswhenaSmartCardexecutesacommand.IntercepttheCommunicationbetweenTerminalandSmartCardThisideacouldbeusedforasimpleinterceptionofthecommunicationbetweenatermin

7、alandasmartcard.ThisideacouldbeusedforT=0andT=1transportprotocolswithoutaPPSandwiththeISO/IEC7816-3standardparameters・Itdon'tsupportmostoftheerrorcorrectionsbetweensmartcardandterminal.TousethisbuildthePCBcircuitandstartaterminalprogramonaPC(likeHyperterm)andsetthefollowi

8、ngparameters:9600bit/s,8databits,1paritybit,2stopbits,nohandshakeandevenparity(9600,E,8,2).RS232